1. Field of the Invention
The present invention relates to a CATV conditional access system in which digital programs are provided in a batch mode from a single digital head end to a plurality of areas. More specifically, the present invention relates to a CATV conditional access system capable of easily allocating channels of analog programs every area.
2. Description of the Related Art
Very recently, community antenna television systems (CATVs) are popularized while multi-media have been developed.
As indicated in FIG. 7, this conventional CATV system is arranged as follows. That is, an analog head end (control center) 1 is installed in each of areas, terminals 2 set into homes of subscribers are connected via cables 3 to this analog head end 1, and then an analog picture signal (video/audio signal) is distributed from this analog head end 1 to the respective terminals 2 via a predetermined picture frequency channel.
Contrary to such an analog CATV system, a digital CATV system will be popularized, because of various needs, for instance, multi-channel broadcasting system, video-on-demand (VOD), and bidirectional communications.
While such an analog CATV system is transferred to a digital CATV system, in the case that an operation station of an existing analog CATV system starts a digital CATV broadcasting service, this operation station is required to commence distributions of digital picture signals without interrupting the distribution services to the subscribers which presently receive the existing analog broadcasting programs.
To meet such a need, the applicant of the present application has proposed such a novel digital integration type CATV system as shown in FIG. 4, since the investment amount required in such a case that the operation station of the existing analog CATV system is transferred from the analog CATV system to the digital CATV system is reduced, and further, the problem such as the installing space occurred when the digital CATV system is newly installed is solved. Accordingly, in order that the present analog CATV system can be smoothly transferred to the digital CATV system, as shown in FIG. 4, a new digital integration type CATV system has been proposed.
In this digital integration type CATV system, one digital head end 10 is installed with respect to a plurality of analog head ends 1A and 1B, and then this digital head end 10 will supply digital programs in a batch mode to the respective analog head ends 1A and 1B. The plural analog head ends. 1A and 1B are installed in the respective areas A and B where the existing analog CATV system has been constructed. Furthermore, the provisions of the program information, and also the managements of the terminal 2 in each of the analog areas A and B are carried out in an integration manner.
However, the existing analog areas A and B own the specific program structures thereof as to the analog programs. The programs provided by the respective areas differ from each other. Otherwise, even when the same program is provided, the channel display numbers are made different from each other in the respective analog areas.
As a result, in such a case that the terminals 2 of the respective analog areas A and B are managed in a batch mode, and/or the program information is supplied in a batch mode by the digital head end 10, the program structures and the channel display numbers in the respective analog areas A and B must be united. Eventually, the loads given to the respective analog head ends 1A and 1B would be considerably increased.
Furthermore, such a fact that the program structures and the channel display numbers, which have been so far employed in the respective analog areas A and B, are changed, may induce unnecessary confusions to the viewers present in the respective analog areas.